Tornado bird boss in a map is borderline impossible to kill

The tornado bird boss in a map summons a huge tornado and this tornado stays in the area for the entire fight and stays on the boss the whole fight. Not sure if this is intended or a bug but I can't see the boss and what the boss is doing, nor can I approach the boss for the entire fight because of the tornado. This boss in the trials of chaos is already a testament to idiocy of people who designed this fight but this mechanic in the maps (which in any other game I would be 100% sure is a bug but in this game anything is possible in the briliant heads of the devs) makes it literally impossible unless you're a ranged build with a huge DPS.